MUSKEGO SANITARY LANDFILL

EPA ID# WID000713180
Last Updated: February, 2015

Site Description

The 56-acre Muskego Sanitary Landfill site is a former animal-rendering plant and gravel quarry located west of the town of Waukesha (pop. 51,000). In 1954, the site owner, Mr. Alfred Wauer, obtained a permit from the city of Muskego to operate the site as a public dumping ground. In 1969, Acme Disposal, a subsidiary of Waste Management of Wisconsin, Inc. (WMWI), leased the property and continued operations at the dump. The site was licensed by the Wisconsin Department of Natural Resources (WDNR) in 1971 as a sanitary landfill. In 1975, WDNR determined that the quality of groundwater was deteriorating in the vicinity of the site and subsequently ordered WMWI to cap and close the site. By 1976, the landfill had been renamed the Muskego Sanitary Landfill and was operated directly by WMWI. Groundwater contamination was discovered in 1982, when WDNR reviewed data in response to a request from WMWI for approval to do repair work on both fill areas. In 1987, WMWI was issued a unilateral administrative order (UAO) to finance and conduct the remedial investigation (RI) at the site. Finally, a second UAO was issued in June 1995 to address the groundwater issues.

Site Responsibility

This site is being addressed through federal, state, and potentially responsible parties' actions and is considered a federal enforcement lead site.

Threats and Contaminants

Groundwater, underlying the site, is contaminated with volatile organic compounds (VOCs) and heavy metals from landfill wastes. Potential health risks are being addressed for individuals who have access to the local groundwater.

Cleanup Progress

In 1982, WDNR found elevated levels of contaminants in four residential wells. The four affected homes were purchased by WMWI. In 1985, the city of Muskego created a public water utility and constructed a system to serve area homes that may have been using contaminated wells. In 1987, the PRPs began a study to determine the nature and extent of groundwater contamination and to identify cleanup alternatives. Approximately 19,820 pounds of liquid solvents and 1,735 tons of contaminated soil and old drums were removed from the site by the potentially responsible parties (PRPs) in spring 1990. A Unlilateral Administrative Order (UAO) was issued to WMWI and over 45 other PRPs in 1992, to design and construct a landfill cap and leachate and gas collection systems. Construction was completed by late 1994. The systems are currently in operation. A new remedy, selected in early 1995, called for a groundwater extraction and treatment pilot system. A UAO was issued in June 1995 for design of this system. This groundwater remedy was designed and constructed as a limited groundwater pump-and-treat system, addressing contamination within the noncontiguous fill area. This work was completed in 1997.

Construction completion for the site was documented in the preliminary close-out report dated September 1997. Since the remedial action resulted in hazardous substances at the site above health-based levels which do not allow for unlimited use and unrestricted exposure, a five-year review is required. The site has moved into the operations and maintenance phase.

The first five-year review was completed in August 1999 (i.e., five years after the initiation of the remedial action activities). The first five year review recommended various followup actions such as continued operation, monitoring, and tuning of the landfill gas extraction system and leachate collection system; continued operation and maintenance of the groundwater extraction system; continued routine environmental monitoring; implementation of the connection of the municipal water supply by the respondents to identified, impacted residents in summer 1999; and the evaluation of the effectiveness of the extraction wells and the system in place. The review also determined that the remedy selected remains protective of human health and the environment.

During 2000, the PRPs completed installing the municipal water supply system and abandoning several monitoring wells.

The second five-year review was completed in September 2004. This review determined that although there is no evidence of current expsoure to any site-related contaminants, the short-term protectivness determination was deferred pending the completion of additional investigations. The review also determined that in order for the remedy to be protective in the long-term, the risk assessment and remedy must address all site-related contamination and the institutional controls must be confirmed to be in-place and effective. Among other on-going and follow-up actions recommended in the five year review was the need for further investigation of the groundwater down gradient from the Muskego Site to evaluate nature, extent and risk posed by any site-related contamination and verification of the institutional controls. To that end, a workplan was approved by U.S. EPA in August 2005 and work has been conducted by the PRPs with appropriate U.S. EPA oversight. A expanded groundwater monitoring report documenting the results of the investigation was completed in 2007.

Five Year Reviews for the Site are on-going since the remedy does not allow for unlimited use and unrestricted exposure. The third five-year review for the Site was initiated in December 2008 and is due by September 2009. The third five-year review was completed and signed on August 21, 2009. The report found the Site to be protective of human health and the environment in the short term. Continued long term protectiveness requires further evaluation of the groundwater remedy, institutional controls, and operation & maintenance of Site remedy and monitoring systems.

An Explanation of Significant Difference (ESD) detailing expanded institutional controls, a monitored natural attenuation (MNA) evaluation, and an evaluation of the remedy components for the Site was completed and signed on September 13, 2010. A Consent Decree which relates to the actions outlined in the ESD and incorporated the existing UAOs was singed and entered in federal court on July 21, 2011.

Site-related documents are available for review of the Muskego Public Library and the Muskego City Hall located at W18258200 Racine Avenue, and on the Site website at epa.gov/region5/sites/muskego/.

The MNA evaluation was completed in 2014 following eight rounds of quarterly sampling with the approval of the June 2014 MNA evaluation report in September. A fourth five-year review report was completed in August 2014 and found the Site to be protective of human health and the environment in the short term.